[PATCH wireless-next v3 18/21] wifi: mac80211: handle UHR Link Reconfiguration frame

[Pooventhiran G]

A UHR Link Reconfiguration Request frame (ST Preparation or Execution)
triggers SMD BSS Transition on the current AP MLD. Userspace needs
reporting of the STA's dynamic context along with such frames so that
the same can be transported to the target AP MLD for setting up the STA
TX and RX queues.

Reserve a field in ieee80211_rx_status that enables drivers to attach
the STA's dynamic context to the corresponding frame. Since the maximum
possible context can grow too big, attach the pointer to the context to
the frame. Add handling for UHR ST Preparation and Execution Request
frames so that the associated context is propagated through cfg80211 and
nl80211 for userspace reporting.

Signed-off-by: Pooventhiran G <pooventhiran.g@xxxxxxxxxxxxxxxx>
---
 include/net/mac80211.h     | 10 +++++++++-
 net/mac80211/ieee80211_i.h |  2 ++
 net/mac80211/rx.c          | 36 ++++++++++++++++++++++++++++++++++++
 3 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 2a595126b1e3..2539b5ffd78b 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1735,6 +1735,10 @@ enum mac80211_rx_encoding {
  * @ack_tx_hwtstamp: Hardware timestamp for the ack TX in nanoseconds. Only
  *	needed for Timing measurement and Fine timing measurement action frames.
  *	Only reported by devices that have timestamping enabled.
+ * @smd_ctx: Pointer to IEEE P802.11bn SMD BSS Transition context information.
+ *	Only needed for ST Preparation Request and ST Execution Request action
+ *	frames. The pointer will be consumed by mac80211; must be kmalloc-ed.
+ *	Indicated by @smd_ctx_valid.
  * @device_timestamp: arbitrary timestamp for the device, mac80211 doesn't use
  *	it but can store it and pass it back to the driver for synchronisation
  * @band: the active band when this frame was received
@@ -1775,12 +1779,15 @@ enum mac80211_rx_encoding {
  * @link_id: id of the link used to receive the packet. Set and used by
  *	mac80211 internally, it uses @freq set by the driver to identify the
  *	correct link per vif.
+ * @smd_ctx_valid: if @smd_ctx has a valid pointer to the ST context. This flag
+ *	is used only for ST Preparation or ST Execution Request frames.
  */
 struct ieee80211_rx_status {
 	u64 mactime;
 	union {
 		u64 boottime_ns;
 		ktime_t ack_tx_hwtstamp;
+		struct ieee80211_smd_ctx *smd_ctx;
 	};
 	u32 device_timestamp;
 	u32 ampdu_reference;
@@ -1814,7 +1821,8 @@ struct ieee80211_rx_status {
 	u8 chains;
 	s8 chain_signal[IEEE80211_MAX_CHAINS];
 	u8 zero_length_psdu_type;
-	u8 link_id:4;
+	u8 link_id:4,
+	   smd_ctx_valid:1;
 };
 
 static_assert(sizeof(struct ieee80211_rx_status) <= sizeof_field(struct sk_buff, cb));
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 9906a62ee99c..82e8542973bc 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -279,6 +279,8 @@ struct ieee80211_rx_data {
 	};
 
 	u8 link_addrs[3 * ETH_ALEN];
+
+	struct ieee80211_smd_ctx *smd_ctx;
 };
 
 struct ieee80211_csa_settings {
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 78967ac95343..a3ffb08f50ba 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -3992,6 +3992,22 @@ ieee80211_rx_h_action(struct ieee80211_rx_data *rx)
 	return RX_QUEUED;
 }
 
+static void
+ieee80211_rx_h_userspace_mgmt_st_req_frame(struct cfg80211_rx_info *info,
+					   struct ieee80211_rx_data *rx)
+{
+	struct ieee80211_mgmt *mgmt = (void *)info->buf;
+	u8 type;
+
+	if (!rx->smd_ctx)
+		return;
+
+	type = mgmt->u.action.uhr_link_reconf_req.type;
+
+	info->st_info.type = type;
+	info->st_info.ctx = rx->smd_ctx;
+}
+
 static ieee80211_rx_result debug_noinline
 ieee80211_rx_h_userspace_mgmt(struct ieee80211_rx_data *rx)
 {
@@ -4003,6 +4019,7 @@ ieee80211_rx_h_userspace_mgmt(struct ieee80211_rx_data *rx)
 		.link_id = rx->link_id,
 		.have_link_id = rx->link_id >= 0,
 		.no_sta = !rx->sta,
+		.st_info.ctx = NULL,
 	};
 
 	/* skip known-bad action frames and return them in the next handler */
@@ -4024,6 +4041,9 @@ ieee80211_rx_h_userspace_mgmt(struct ieee80211_rx_data *rx)
 	    ieee80211_is_ftm(rx->skb)) {
 		info.rx_tstamp = ktime_to_ns(skb_hwtstamps(rx->skb)->hwtstamp);
 		info.ack_tstamp = ktime_to_ns(status->ack_tx_hwtstamp);
+	} else if (ieee80211_is_st_prep_req(rx->skb) ||
+		   ieee80211_is_st_exec_req(rx->skb)) {
+		ieee80211_rx_h_userspace_mgmt_st_req_frame(&info, rx);
 	}
 
 	if (cfg80211_rx_mgmt_ext(&rx->sdata->wdev, &info)) {
@@ -5630,10 +5650,18 @@ void ieee80211_rx_list(struct ieee80211_hw *hw,
 	struct ieee80211_supported_band *sband;
 	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
+	struct ieee80211_smd_ctx *smd_ctx = NULL;
 	struct ieee80211_rx_data rx = {};
 
 	WARN_ON_ONCE(softirq_count() == 0);
 
+	/* cache the pointer to free it later */
+	if (status->smd_ctx_valid) {
+		smd_ctx = status->smd_ctx;
+		status->smd_ctx = NULL;
+		status->smd_ctx_valid = false;
+	}
+
 	if (WARN_ON(status->band >= NUM_NL80211_BANDS))
 		goto drop;
 
@@ -5765,6 +5793,12 @@ void ieee80211_rx_list(struct ieee80211_hw *hw,
 
 	kcov_remote_start_common(skb_get_kcov_handle(skb));
 
+	rx.smd_ctx = smd_ctx;
+
+	if (WARN_ONCE((status->flag & RX_FLAG_8023) && rx.smd_ctx,
+		      "802.3 packet but with IEEE P802.11bn SMD context"))
+		goto drop;
+
 	/*
 	 * Frames with failed FCS/PLCP checksum are not returned,
 	 * all other frames are returned without radiotap header
@@ -5784,10 +5818,12 @@ void ieee80211_rx_list(struct ieee80211_hw *hw,
 			__ieee80211_rx_handle_packet(hw, link_pubsta, skb,
 						     list, &rx);
 	}
+	kfree(smd_ctx);
 
 	kcov_remote_stop();
 	return;
  drop:
+	kfree(smd_ctx);
 	kfree_skb(skb);
 }
 EXPORT_SYMBOL(ieee80211_rx_list);

-- 
2.34.1